Valve



April 1959 D. K. HANINK 2,881,750

VALVE Filed March 29, 1956 EASE MEML Inventor Attorney VALVE Dean K. Hanink, Indianapolis, Ind., assignoito General Motors Corporation, Detroit, Mich.,' a corporation of Delaware Application March 29, 1955, serial N 574,375 13 Claims. 31. 123-188).

gasolines in particular are extremely detrimental and:

greatly shorten the valve lifein' such engines. The valve failure may occur becauseofhigh temperature corrosion of the valve seating faceor. because of corrosion of the stemimmediately beneath the valve head. Severe corrosion of this stem results in its necking down to the point where the stem will fracture. The primary object of. the present invention is to provide a valve for an internal combustion engine having a greatly increased operating life. Other object's aiid advantages of the invention will become more apparent as the description proceeds. l

' In accordance with the present invention. there is provideda valve for internal combustion engines having at or adjacent its surface, at least at the valveseat-faeing portion thereof; a thin layer of an alloy of aluminum or aluminum base alloy and .the'base metal of the valve. For best results the valve also has an extremely thin layerfof aluminum or aluminum base alloy on said all'oylayer'. I have found that the layer or layers 'sliouldbe extremely thin to provide valves having the required. characteristics such that the surface alloy layer does not spall or flake E. p The alloying of the surface portion of the valve with aluminum or aluminum. base alloy may ,be carried ou't-in any desired manner.

conditions that the aluminum willlform anallo'y with the valve material and result in the desired requisitethinness.

One very satisfactory method'is to apply the aluriiinumbr-v aluminum base alloy in accordance with any of the procedures described in Patent 2,569,097, ownedby the thereafter removing the valve from the aluminum; then rinsing for a short time of not more lthanfifteensecoiids in the fluxing salt, and finally removing excesscoating material as by meansof an air blast, rapid rotation of the valve or by vibrating the valve rapidly. The valve ,as thus treated has an extremely thin and :uniform coating ofaluminum bonded tothe base metal by an intermediate; extremely thin and'uniform layer of an alloy of alumi num with the base metal.

One method is to apply molten aluminum or aluminum base alloy to the valve undersueh' 2,881,750 aateated Apr. 14, 1959 2 Other satisfactory methods of coating the valve and forming the alloy of aluminum therewith are disclosed in copending application of Hanink, Shoudy, IL, and Thomson, Serial No. 459,093; filed September 29, 1954,-

ahd. owned by the assignee of the present invention.

' In processing the valve, the base metal from which the valve is made is machinedsubstantially to final dimensions before the aluminum alloying takes place. Since the preferredmethod. results in an extremely thin and u n i forhi coating of aluminum on the valve it is unnecessary to grind or otherwise remove any of the aluminum 'c'oat' ing prior to use of the valve' Hci'wever, where a thicker coating of aluminum is produced during the coating step,

the valve seat facing may be honed or otherwise processedto rjmove some or. all ofthe aluminum coating overlay without materially affecting theintermediate alloy layer.

The surfaces of the valve to be coated are preferably cleaned prior to the aluminum coating andalloying oper} atiorr. One satisfactory method-is to clean the valves ina molten electrolytic caustic salt (such for example as a commercially available product called Kolene) a't 900 F. The parts then may be water washed and thereafter preferably further cleaned by acid pickling. A suitable acid pickling bath, is, an aqueous, solution, containing, about 21.0% hydrofluoric acid, 7.0%., sulphuric acid, and 10% nitric acid. Insomecases the..v.alv.es may only require a vapor degreasing treatment in chlorinated solvent prior to, the, aluminum, coating and, alloying operation.

Mechanical cleaning methods, such as grit blasting, sand;

blasting, etc., may be employed in some cases to supplementthe chemical cleaning treatments. In addition to forming a clean surface for adherence of the coating ma terial, their; n n other surface defects in the valves.

After the valve has been cleaned, the portion thereofon which it is desired that no coating be appliedmaybe treated with as'nitaiaie stop-oft eating to prevent the aluminum nos! 'saaaiag'ia at aua' is with ftheLbase.

je'cted to hot combustion gases, typical examples being. intake and exhaust valves of the poppet type, flapper valves,- butterfly valves and the like. The base metal of which thevalve is formed-may beany suitable valve material and especially any material of the type or types heretoforeemployed for valves. ,Typical and illustrative examples of valve materials are, the following:

Balance substantially all iron.

seamen; snow as any cracks or If additional strength and density of.

-.Example'-3 Percent Carbon 0.45 Manganese 0.40 Silicon 3.25 Chromium 8.50" Balance. iron.

' Example 4 Percent Carbon --r-- .20 Manganese 1.40 Silicon 0.80 Chromium 21.00. Nickel 12.00 Balance iron. .15

Example 5 Percent Carbon 0.45 Manganese (max.) 0.70 Silicon 0.55 Chromium 14.00 Nickel 14.00 Molybdenum 0.35 Tungsten, 2.50 Balance iron.

Example 6 1 Percent Carbon 0.40 Manganese 1.0 Silicon 3.0 Chromium 19.0 Nickel 8.0 Balance iron. 1

Example 7 Percent Carbon .04 Manganese .50 Silicon .40 Columbium 1.00 Aluminum .70 Iron 7.00 Chromium 15.00 Balance nickel.

Example 8 v Percent Carbon 1.0 Manganese .25 Silicon I 1.25 Chromium 28.00 Tungsten 4.50 Iron 2.00 Balance cobalt.

The alloy of aluminum with the valve material should in all cases be'extremely thin. this alloy will have a thickness within the range of from 0.00005 inch to 0.00.15 inch and the aluminum have a thickness within the range of from 0.00 inch to 0.004 inch. A very satisfactory alloy layer is one having a thickness within the range of from 0.0002 inch to 0.001 inch. In some applications, it is of further advantage to have a minimum thickness of the alloy layer of 0.0005 inch. It is presently preferred, especially with valve steels of the type of Example 1 above, that the layer of the alloyof num alloy layer and thin aluminum layer burn less than 10,000 miles under similar test conditions.

The coating material may be either aluminum or any known aluminum base alloy. By Faluminum base alloy In general, the layer of is meant an alloy of'aluminumwhich contains about 80% or more of aluminum. Where the word aluminum is used in the claims to refer to the coating material, it is intended to include not only pure aluminum, or commercially pure aluminum, but also the aluminum base alloys containing about 80% or more of aluminum.

Reference is herewith made to the accompanying drawings in which:

Figure 1 is a view partially in" section of a poppet valve being'in closed position on a valveseat. 1

Figure 2 is a view generally similar to Figure 1 and showingapoppet valve with a coating only on the valve seat facing portion of the valve.

Figure 3 is aphotomicrog'naph showing a portion of the base metal of the valve, a layer of an alloy of aluminum with the valve metal and a layer of aluminum on the alloy layer.

In Figure 1 there is shown a poppet valve indicated generally by 10 and having a stem 12 and head 14. The entire head and-upper portion of the valve stem which in engine assembly .Will not contact valve guide are provided with a coating 16 of aluminum or aluminum base allo'yand an intermediate alloy layer 17 of aluminum and the base metal ofthe valve. coating16 and alloy layer 17 are exaggerated in the drawing. The valve of Figure .1 is shown in closed position .on the valve seat 20, the valve having a tapered valve seat facing 22 in engagementwith the valve seat. Figure 2 shows a valve 30 havinga stem 32 and a head 34. tapered valve seat facing portion36of the valve is provided with. a coating 40 of aluminum or aluminum base alloy and an intermediate layer 41 of aluminum and the basemetal of. the valve. The thicknesses of the coating 0 and the, alloy layer 41 are exaggerated in the drawing. In-Figure 2 the valve. is shown in closed position with the tapered valve seat facing-36 contacting the corresponding tapered surface 46 of the valve seat. In the photomicrographshown in Figure 3, the base metal of the valve is indicated at 50, while 52 indicates the alloy of aluminum .with the base-metal and 54 the outermost layer.- of aluminum. The magnification of the photo- -micrograph' of Figure 3 has been measured at 200x.

Thepresent invention results in valves having greatly increased life and at a relatively small cost. The valve is one of high quality in which there is provided a continuous chemical bond at the interface of the coating metal and base metal .of the valve. The process provides a uniform aluminum coating on the appropriate surfaces of the valve and the thickness of this coating can be closely regulated. Inturn, the thickness of the intermediate iron-aluminum-(or' other. alloy of alumi- '.num and base metal of the valve) may be controlled. It is important that the layer of intermediate alloybc thin-as hereinbefore described to prevent spalling or While this invention has been described by reference toeertain preferred embodiments and specific examples of preferred materials and conditions, it will be under-- stood the invention is not to be limited thereby as numerous; changes and modifications will be apparent to those skilled in the art without departing from the spirit an'dprinciples of-the invention.

1: A'valve h-aving a surface portion coated with a thin layer ofal-uminum, said aluminum being bonded toth'e base material of the valve w-ith an alloy of aluminu mwith said base material having a thicknessbetween 0.00005" and 0.0015".

having. a coating -on its head and neck portions, the .valve The thicknesses of the In :vthe construction shown in Figure 2 only the- 2. A valve formed of a ferrous base material having a surface portion coated With a thin layer of aluminum, said aluminum being bonded to said ferrous base material with an alloy of aluminum with said ferrous base material having a thickness between 0.00005 and 0.0015".

3. A valve comprising a ferrous base material formed in the shape of a poppet valve, a thin aluminum coating on the head of said valve, and a layer of iron-aluminum alloy intermediate said ferrous base material and said aluminum coating and having a thickness between 0.00005 and 0.0015.

4. A valve comprising a ferrous base material formed in the shape of a poppet valve, a thin aluminum coating on the valve seat facing of said valve, and an intermediate layer of an iron-aluminum alloy having a thickness between 0.00005 and 0.0015.

5. A valve formed of a ferrous base material, a layer having a thickness between 0.00005" and 0.0015 of a alloy of aluminum with said ferrous base material, and an extremely thin layer of aluminum not in excess of 0.004" on said alloy layer.

6. A poppet valve comprising a ferrous base material in poppet valve form having a valve seat facing portion and an adherent layer having a thickness between 0.00005" and 0.001 of an alloy of aluminum With the ferrous base metal at the valve seat facing portion of said valve.

7. A valve comprising a ferrous base material in poppet valve form having a valve seat facing portion, an adherent layer of an alloy of aluminum with the ferrous metal at the valve seat facing portion of said valve having a thickness of 0.00005" to 0.001 and an extremely thin layer of aluminum having a thickness not in excess of 0.004 bonded to said alloy layer.

8. A valve having a valve seat facing portion and having an adherent layer of an alloy of aluminum with the base metal of the valve at the valve seat facing portion of the valve, said alloy having a thickness within the range of 0.00005 and 0.0015".

9. A valve comprising a ferrous base material in poppet valve form, having an adherent layer of an alloy of aluminum with the ferrous metal on the valve seat facing portion of said valve, having a thickness within the range of about 0.0002" to 0.001" and a very thin layer of aluminum having a thickness not in excess of 0.004 bonded to said alloy layer.

10. A valve comprising a ferrous base material in poppet valve form, having an adherent layer of an alloy of aluminum with the ferrous metal on the valve seat facing portion of said valve, having a thickness Within the range of about 0.0005 to 0.001 and-an extremely thin layer of aluminum having a thickness not in excess of 0.004" bonded to said alloy layer.

11. A poppet valve having an adherent layer of an alloy of aluminum with the valve seat facing portion of said valve, having a thickness within the range of about 0.0002" to 0.001.

12. A poppet valve having an adherent layer of an alloy of aluminum with the valve seat facing portion of said valve, having a thickness within the range of about 0.0005" to 0.001".

13. A poppet valve formed of ferrous-base material having a valve seat facing portion, an adherent layer of an alloy of aluminum with the ferrous metal in the valve seat facing portion having a thickness Within the range of 0.00005" to 0.0015" and an extremely thin layer of aluminum having a thickness not over 0.004" adherently bonded to said alloy layer.

References Cited in the file of this patent FOREIGN PATENTS Great Britain May 17, 1946 Great Britain Mar. 21, 1949 OTHER REFERENCES 

1. A VALVE HAVING A SURFACE PORTION COATED WITH A THIN LAYER OF ALUMINUM, SAID ALUMINUM BEING BONDED TO THE BASE MATERIAL OF THE VALVE WITH AN ALLOY OR ALUMINUM WITH SAID BASE MATERIAL HAVING A THICKNESS BETWEEN 0.00005" AND 0.0015" 